Remove treatAutoAsYGValueUndefined flag (#41033)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/41033

This has been rolled out with the false value (previous client-default of false). The open-source value was already false.

Changelog: [Internal]

Reviewed By: NickGerleman, sammy-SC

Differential Revision: D50362517

fbshipit-source-id: 577a2ead047b30d196409a26fd5385f333f20b18

packages/react-native/ReactCommon/react/renderer/components/view/conversions.h

@@ -398,8 +398,7 @@ inline void fromRawValue(
   } else if (value.hasType<std::string>()) {
     const auto stringValue = (std::string)value;
     if (stringValue == "auto") {
-      result = context.treatAutoAsYGValueUndefined() ? YGValueUndefined
-                                                     : YGValueAuto;
+      result = YGValueAuto;
       return;
     } else {
       if (stringValue.back() == '%') {

packages/react-native/ReactCommon/react/renderer/core/PropsParserContext.cpp

@@ -1,27 +0,0 @@
-/*
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-#include "PropsParserContext.h"
-
-#include <react/config/ReactNativeConfig.h>
-
-namespace facebook::react {
-
-bool PropsParserContext::treatAutoAsYGValueUndefined() const {
-  if (treatAutoAsYGValueUndefined_ == std::nullopt) {
-    auto config =
-        contextContainer.find<std::shared_ptr<const ReactNativeConfig>>(
-            "ReactNativeConfig");
-    treatAutoAsYGValueUndefined_ = config && *config != nullptr
-        ? (*config)->getBool("react_fabric:treat_auto_as_undefined")
-        : false;
-  }
-
-  return *treatAutoAsYGValueUndefined_;
-}
-
-} // namespace facebook::react

packages/react-native/ReactCommon/react/renderer/core/PropsParserContext.h

@@ -29,12 +29,6 @@ struct PropsParserContext {
 
   const SurfaceId surfaceId;
   const ContextContainer& contextContainer;
-
-  // Temporary feature flags
-  bool treatAutoAsYGValueUndefined() const;
-
- private:
-  mutable std::optional<bool> treatAutoAsYGValueUndefined_;
 };
 
 } // namespace facebook::react